Additive for Positive Electrode, Positive Electrode Including the Same, and Rechargeable Lithium Battery Including the Same

The present application claims priority to and the benefit of Korean Patent Application No. 10-2024-0080788, filed on Jun. 21, 2024, in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference.

One or more embodiments of the present disclosure relate to an additive for a positive electrode of a rechargeable lithium battery.

Recently, with the rapid spread and popularization of electronic devices that use batteries, such as mobile phones, laptop computers, and/or electric vehicles, the demand for such batteries, e.g., rechargeable batteries, with relatively high energy density and high capacity has been rapidly increased. Accordingly, research and development efforts have been actively focused (conducted) on improving the performance of such rechargeable batteries, e.g., rechargeable lithium batteries.

The rechargeable lithium battery includes a positive electrode and a negative electrode, each containing an active material capable of intercalation and deintercalation of lithium ions, along with an electrolyte solution. Electrical energy is produced by oxidation and reduction reactions when the lithium ions are intercalated and deintercalated into/from the positive electrode and the negative electrode (e.g., intercalated into the positive electrode and/or deintercalated from the negative electrode during the discharge process).

One or more aspects of the present disclosure are directed toward a positive electrode including a functional additive.

One or more aspects of the present disclosure are directed toward a preparation method of a rechargeable lithium battery in which the functional additive is added.

Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments of the disclosure.

According to one or more embodiments of the present disclosure, a positive electrode active material slurry includes a functional additive, a positive electrode active material, a conductive material, and a binder, wherein the functional additive includes a compound containing a substituted or unsubstituted pyrazole group.

According to one or more embodiments of the present disclosure, a rechargeable lithium battery includes a positive electrode, a negative electrode, and an electrolyte layer between the positive electrode and the negative electrode, the positive electrode includes a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector, and the negative electrode includes a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector, and the positive electrode active material layer is formed by using the positive electrode active material slurry of present disclosure.

According to one or more embodiments of the present disclosure, a preparation method of a rechargeable lithium battery includes preparing a positive electrode, preparing a negative electrode, and combining the positive electrode and the negative electrode to prepare the rechargeable lithium battery, the preparing of the positive electrode includes mixing a positive electrode active material, a conductive material, a binder, and a functional additive to form a positive electrode active material slurry, and applying the positive electrode active material slurry to a positive electrode current collector to form a positive electrode active material layer, and the functional additive includes a compound containing a substituted or unsubstituted pyrazole group.

In order to fully understand the configurations and aspects of the present disclosure, one or more embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. The present disclosure may, however, be embodied in one or more suitable forms and should not be construed as limited to example embodiments set forth herein, and one or more suitable changes and modifications may be made. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art to which the present disclosure pertains.

In the present disclosure, it will be understood that, if (e.g., when) an element is referred to as being on another element, the element may be directly on the other element or intervening elements may be present therebetween. In contrast, if (e.g., when) an element is referred to as being “directly on” another element, there are no intervening elements present. In the drawings, thicknesses of components may be exaggerated for effectively explaining the technical contents. Like reference numerals or symbols refer to like elements throughout the present disclosure, and duplicative descriptions thereof may not be provided for conciseness.

In the present disclosure, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, the utilization of “may” when describing embodiments of the present disclosure refers to “one or more embodiments of the present disclosure.” In addition, unless otherwise specially noted, the phrase “A or B” or “A and/or B” or “A/B” may indicate “including A but not B, B but not A, or A and B.” The terms “comprise(s)/include(s)” and/or “comprising/including” used in the present disclosure do not exclude the presence or addition of one or more other components.

In the present disclosure, the term “combination thereof” may refer to a mixture, a stack, a composite, a copolymer, an alloy, a blend, and a reaction product of components.

Unless otherwise defined in the disclosure, a particle diameter/size may be an average particle diameter/size. Also, the particle diameter/size refers to an average particle diameter/size (D50) which refers to a diameter/size of particles at a cumulative volume of about 50 vol % in a particle size distribution. D50 refers to the average diameter (or size) of particles whose cumulative volume corresponds to 50 vol % in the particle size distribution (e.g., cumulative distribution), and refers to the value of the particle size corresponding to 50% from the smallest particle when the total number of particles is 100% in the distribution curve accumulated in the order of the smallest particle size to the largest particle size. The average particle diameter/size (D50) may be measured by a method widely suitable to those skilled in the art, for example, may be measured by a particle size analyzer, for example, HORIBA, LA-950 laser particle size analyzer, or may also be measured using a transmission electron microscope (TEM) image or a scanning electron microscope (SEM) image. In one or more embodiments, the average particle diameter/size may be measured by a measuring device using dynamic light-scattering, wherein the number of particles is counted for each particle size range by performing data analysis, and an average particle diameter/size (D50) value may then be obtained by calculation therefrom. Also, the average particle diameter/size may be measured using a laser diffraction method. When measured by the laser diffraction method, for example, after dispersing particles to be measured in a dispersion medium, the dispersion medium is introduced into a commercial laser diffraction particle size measurement instrument (e.g., Microtrac MT 3000) and irradiated with ultrasonic waves of about 28 kHz at an output of about 60 W, and the average particle diameter/size (D50) based on about 50% of particle size distribution in the measurement instrument may then be calculated. In the present disclosure, when particles are spherical, “diameter/size” indicates an average particle diameter/size, and when the particles are non-spherical, the “diameter/size” indicates a major axis length.

is a simplified conceptual diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure. Referring to, a rechargeable lithium battery may include a positive electrode, a negative electrode, a separator, and an electrolyte solution ELL.

The positive electrodeand the negative electrodemay be spaced and/or apart (e.g., spaced apart or separated) from each other with the separatortherebetween. The separatormay be arranged between the positive electrodeand the negative electrode. The positive electrode, the negative electrode, and the separator(i.e., all three components) may be in contact with the electrolyte solution ELL. Additionally, the positive electrode, the negative electrode, and the separator(i.e., they all) may be in and/or impregnated with the electrolyte solution ELL.

The electrolyte solution ELL may be a medium for transferring lithium ions between the positive electrodeand the negative electrode. In the electrolyte solution ELL, the lithium ions may move through the separatortoward the positive electrodeor the negative electrode.

In one or more embodiments, a rechargeable battery containing a gel polymer electrolyte (or a semisolid electrolyte) or a solid electrolyte may include an electrolyte layer. In these embodiments, the electrolyte layer may substitute for roles of the separatorand the electrolyte solution ELL.

The positive electrodefor a rechargeable lithium battery may include a current collector COLand a positive electrode active material layer AMLon the current collector COL. The positive electrode active material layer AMLmay include a positive electrode active material (e.g., in a form of particles) and may further include a binder and/or a conductive material (e.g., electron conductor). An amount of the positive electrode active material in the positive electrode active material layer AMLmay be about 90 wt % to about 99.5 wt % based on 100 wt % of a total weight of the positive electrode active material layer AML. An amount of each of the binder and the conductive material may be about 0.5 wt % to about 5 wt % based on 100 wt % of the total weight of the positive electrode active material layer AML. In one or more embodiments, the positive electrode active material layer AMLmay further include a functional additive ADD. The positive electrode according to one or more embodiments of the present disclosure will be described in more detail later. In one or more embodiments, aluminum (Al) may be used for the current collector COL, but embodiments of the present disclosure are not limited thereto.

The positive electrode active material in the positive electrode active material layer AMLmay include a compound (lithiated intercalation compound) that is capable of reversibly intercalating and deintercalating lithium. For example, at least one of a composite oxide of lithium and a metal selected from among cobalt, manganese, nickel, and one or more (e.g., any suitable) combinations thereof may be used.

The composite oxide may be a lithium transition metal composite oxide. Specific examples of the composite oxide may include lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, cobalt-free nickel-manganese-based oxides, or a (e.g., any suitable) combination thereof.

As an example, a compound represented by any one selected from among the following formulas may be used: LiAXOD(0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); LiMnXOD(0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); LiNiCoXOD(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0<α<2); LiNiMnXOD(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0<α<2); LiNiCoLGO(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, and 0≤e≤0.1); LiNiGO(0.90≤a≤1.8 and 0.001≤b≤0.1); LiCoGO(0.90≤a≤1.8 and 0.001≤b≤0.1); LiMnGO(0.90≤a≤1.8 and 0.001≤b≤0.1); LiMnGO(0.90≤a≤1.8 and 0.001≤b≤0.1); LiMnGPO(0.90≤a≤1.8 and 0≤g≤0.5); LiFe(PO)(0≤f≤2); and LiFePO(0.90≤a≤1.8).

In the above formulas, A is Ni, Co, Mn, or a (e.g., any suitable) combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a (e.g., any suitable) combination thereof; D is O, F, S, P, or a (e.g., any suitable) combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a (e.g., any suitable) combination thereof; and Lis Mn, Al, or a (e.g., any suitable) combination thereof.

The positive electrode active material may be, for example, a high nickel-based positive electrode active material having a nickel content of greater than or equal to about 80 mol %, greater than or equal to about 85 mol %, greater than or equal to about 90 mol %, greater than or equal to about 91 mol %, or greater than or equal to about 94 mol % and less than or equal to about 99 mol %, based on 100 mol % of the total metal excluding lithium in the lithium transition metal composite oxide. The high-nickel-based positive electrode active material may be capable of realizing high capacity and thus may be applied to a high-capacity, high-density rechargeable lithium battery. That is, in one or more embodiments, the high-nickel-based positive electrode active material, capable of achieving high capacity, may be applied to high-capacity, high-density rechargeable lithium batteries.

The binder serves to attach the positive electrode active material particles well to each other and also to attach the positive electrode active material well to the current collector COL. Examples of the binder may include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, a styrene-butadiene rubber, a (meth)acrylated styrene-butadiene rubber, an epoxy resin, a (meth)acrylic resin, a polyester resin, nylon, a polymer including ethylene oxide, and/or the like, as non-limiting examples.

The conductive material may be used to impart conductivity (e.g., electrical conductivity) to the electrode. Any material that does not cause chemical change (e.g., does not cause an undesirable chemical change in the rechargeable lithium battery) and conducts electrons may be used in the battery. Examples of the conductive material may include a carbon-based material such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, a carbon fiber, a carbon nanofiber, and a carbon nanotube; a metal-based material containing copper, nickel, aluminum, silver, and/or the like. in a form of a metal powder or a metal fiber; a conductive polymer such as a polyphenylene derivative; and/or a (e.g., any suitable) mixture thereof.

The negative electrodefor a rechargeable lithium battery may include a current collector COLand a negative electrode active material layer AMLon the current collector COL. The negative electrode active material layer AMLmay include a negative electrode active material (e.g., in a form of particles), and may further include a binder and/or a conductive material (e.g., an electrically conductive material).

For example, the negative electrode active material layer AMLmay include about 90 wt % to about 99 wt % of the negative electrode active material, about 0.5 wt % to about 5 wt % of the binder, and about 0 wt % to about 5 wt % of the conductive material, based on 100 wt % of a total weight of the negative electrode active material layer.

The binder may serve to attach the negative electrode active material particles well to each other and also to attach the negative electrode active material well to the current collector COL. The binder may include a non-aqueous (e.g., water-insoluble) binder, an aqueous (water-soluble) binder, a dry binder, and/or a (e.g., any suitable) combination thereof.

The non-aqueous binder may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, and/or a (e.g., any suitable) combination thereof.

The aqueous binder may be selected from among a styrene-butadiene rubber, a (meth)acrylated styrene-butadiene rubber, a (meth)acrylonitrile-butadiene rubber, a (meth)acrylic rubber, a butyl rubber, a fluoro rubber, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, an ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, a polyester resin, a (meth)acrylic resin, a phenol resin, an epoxy resin, polyvinyl alcohol, and/or a (e.g., any suitable) combination thereof.

When an aqueous binder is used as the negative electrode binder, a cellulose-based compound capable of imparting viscosity may be further included. The cellulose-based compound may include at least one of carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or an alkali metal salt thereof. The alkali metal may include Na, K, or Li.

The dry binder may be a polymer material that is capable of being fibrous. For example, the dry binder may be polytetrafluoroethylene, polyvinylidene fluoride, a polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a (e.g., any suitable) combination thereof.

The conductive material may be used to impart conductivity (e.g., electrical conductivity) to the electrode. Any material that does not cause chemical change (e.g., does not cause an undesirable chemical change in the rechargeable lithium battery) and that conducts electrons can be used in the battery. Non-limiting examples thereof may include a carbon-based material such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, a carbon fiber, a carbon nanofiber, and a carbon nanotube; a metal-based material including copper, nickel, aluminum, silver, and/or the like, in a form of a metal powder or a metal fiber; a conductive polymer such as a polyphenylene derivative; and/or a (e.g., any suitable) mixture thereof.

The current collector COLmay include a copper foil, a nickel foil, a stainless-steel foil, a titanium foil, a nickel foam, a copper foam, a polymer substrate coated with a conductive metal, and/or a (e.g., any suitable) combination thereof.

The negative electrode active material may include a material that reversibly intercalates/deintercalates lithium ions, a lithium metal, a lithium metal alloy, a material capable of doping/dedoping lithium, or a transition metal oxide.

The material that reversibly intercalates/deintercalates lithium ions may include a carbon-based negative electrode active material, such as, for example, crystalline carbon, amorphous carbon and/or a (e.g., any suitable) combination thereof. The crystalline carbon may be graphite such as non-shaped, sheet-shaped, flake-shaped, sphere-shaped, or fiber-shaped natural graphite or artificial graphite. The amorphous carbon may be a soft carbon, a hard carbon, a mesophase pitch carbonization product, calcined coke, and/or the like.

The lithium metal alloy includes an alloy of lithium and a metal selected from among Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

The material capable of doping/dedoping lithium may be a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material may include silicon, a silicon-carbon composite, SiO(0<x≤2), a Si-Q alloy (where Q is selected from among an alkali metal, an alkaline-earth metal, a Group 13 element, a Group 14 element (excluding Si), a Group 15 element, a Group 16 element, a transition metal, a rare earth element, and/or a (e.g., any suitable) combination thereof), and/or a (e.g., any suitable) combination thereof. The Sn-based negative electrode active material may include Sn, SnO(0<x≤2), e.g., SnO, a Sn-based alloy, and/or a (e.g., any suitable) combination thereof.

The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one or more embodiments, the silicon-carbon composite may be in a form of silicon particles and amorphous carbon applied onto the surface of each of the silicon particles. For example, the silicon-carbon composite may include a secondary particle (core) in which primary silicon particles are assembled, and an amorphous carbon coating layer (shell) on the surface of the secondary particle. The amorphous carbon may also be between the primary silicon particles, and for example, the primary silicon particles may be each coated with the amorphous carbon. The secondary particle may exist dispersed in an amorphous carbon matrix.

The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core including crystalline carbon and silicon particles and an amorphous carbon coating layer on a surface of the core.

The Si-based negative electrode active material or the Sn-based negative electrode active material may be used in combination with a carbon-based negative electrode active material.

Depending on the type or kind of the rechargeable lithium battery, the separatormay be present between the positive electrodeand the negative electrode. The separatormay include polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof, or a mixed multilayer film such as a polyethylene/polypropylene two-layer separator, polyethylene/polypropylene/polyethylene three-layer separator, polypropylene/polyethylene/polypropylene three-layer separator, and/or the like.

The separatormay include a porous substrate and a coating layer including an organic material, an inorganic material, and/or a (e.g., any suitable) combination thereof on a surface (e.g., one or both surfaces (e.g., two opposite surfaces)) of the porous substrate.

The porous substrate may be a polymer film formed of any one polymer selected from among polyolefin such as polyethylene and polypropylene, polyester such as polyethylene terephthalate and polybutylene terephthalate, polyacetal, polyamide, polyimide, polycarbonate, polyether ketone, polyarylether ketone, polyether ketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene oxide, a cyclic olefin copolymer, polyphenylene sulfide, polyethylene naphthalate, a glass fiber, TEFLON, and polytetrafluoroethylene, or a copolymer or a mixture of two or more thereof.

The organic material may include a polyvinylidene fluoride-based polymer or

a (meth)acrylic polymer.

The inorganic material may include inorganic particles selected from among AlO, SiO, TiO, SnO, CeO, MgO, NiO, CaO, GaO, ZnO, ZrO, YO, SrTiO, BaTiO, Mg(OH), boehmite, and/or a (e.g., any suitable) combination thereof, but the present disclosure is not limited thereto.

The organic material and the inorganic material may be mixed in one coating layer, or a coating layer including an organic material and a coating layer including an inorganic material may be stacked.